Outsize Saxon on a mountain (4)
I believe the answer is:
ossa
'mountain' is the definition.
(I've seen this before)
'outsize saxon on a' is the wordplay.
'outsize' becomes 'os'.
'saxon' becomes 's' (this might be a standard abbreviation I've not previously seen).
'on' is a charade indicator (letters next to each other).
'os'+'s'+'a'='OSSA'
Can you help me to learn more?
(Other definitions for ossa that I've seen before include "To heap Pelion on -- is to compound difficulties" , "Legendary mountain" , "Greek mountains" , "So as to turn to bones" , "mountain in Thessaly" .)